I have one of these. She frustrates me to no end. Nothing is safe from her, not even other children. She's good right now but she goes through "stages" lasting a week or 2 of hitting other children. She's the same way at home, it's not daycare behaviour and her parents are just as frustrated. I feel you pain! haha.

I'm slowly learning ways to adapt and help her modify her behaviour. Food is served in small portions on a tray in a highchair, no booster for her. If she throws her plate once it is gone for the rest of the meal. Food smeared or thrown signals the end of the meal she is washed and left in her highchair until everyone else has finished (that's the rule here anyway, no one is allowed up until everyone is finished). 2 instances of hitting and she is put in a playpen for 10 minutes or so with some toys and her sippy cup, right next to us not isolated, just unable to hit until she reigns in her temper. The playpen rule is also in effect for book tearing, toy throwing, bin dumping... all the things a destructor is famous for haha. Her parents do the same at home and it's really working.

Hope it gets better!